Last major update issued on April 4, 2004 at 03:40 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update April 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update April 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update April 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2003 (last update January 16,
2004)]
[Archived reports (last update March 28, 2004)]
The geomagnetic field was quiet to minor storm on April 3. Solar wind speed ranged between 333 and 518 km/sec. A solar wind shock was observed at SOHO at 08:49 UTC as the CME observed on March 31 arrived. The interplanetary magnetic field was at times strongly southwards after the shock.
Solar flux measured at 20h UTC on 2.8 GHz was 107.4. The planetary A
index was 23 (STAR Ap - based on the mean of three hour interval ap indices: 24.6).
Three hour interval K indices: 23434455 (planetary), 33334545 (Boulder).
The background x-ray flux is at the class B1-B2 level.
At midnight there were 5 spotted regions on the visible disk. The solar flare activity level was very low. No C class events were recorded during the day.
Region 10581 decayed slowly and quietly.
Region 10582 decayed further and lost all spots outside of the main penumbra.
Region 10587 developed a penumbra in the intermediate spot section, no significant changes were observed elsewhere in
the region.
Region 10588 was quiet and stable.
Spotted regions not numbered by NOAA/SEC:
[S380] This region emerged on April 3 as a reversed polarity group just south of region 10588. Location at midnight:
S16E51.
April 1-3: No fully or partly earth directed CME observed.
Coronal hole history (since late October 2002)
Compare today's report with the situation one solar rotation ago: 28
days ago 27 days ago 26 days ago
An elongated, recurrent trans equatorial coronal hole (CH88) will be in a geoeffective position on April 1-7.
Processed SOHO/EIT 284 image at 00:12 UTC on March 18. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be unsettled to minor storm on April 4-6, first due to the CME which arrived on April 3, then due to a high speed stream from coronal hole CH88. Quiet to active is likely on April 7-10 under the influence of the high speed stream from coronal hole CH88.
Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is very poor to useless. Propagation along long distance north-south paths is poor. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay, later Radio Vibración (Venezuela) was noted as well. Otherwise some of the usual stations from Brazil could be heard with the best signals on 740, 980 and 1010 kHz].
| Coronal holes (1) | Coronal mass ejections (2) | M and X class flares (3) |
 |
 |
|
1) Effects from a coronal hole could reach Earth within the next 5 days. When the high speed stream has arrived
the color changes to green.
2) Material from a CME is likely to impact Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next 48 hours.
Green: 0-20% probability, Yellow: 20-60% probability, Red: 60-100% probability.
Compare to the previous day's image.
Data for all numbered solar regions according to the Solar Region Summary provided by NOAA/SEC. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SEC or where SEC has observed no spots. SEC active region numbers in the table below and in the active region map above are the historic SEC/USAF numbers.
| Active region | Date numbered | SEC spot count |
STAR spot count |
Location at midnight | Area | Classification | Comment |
|---|---|---|---|---|---|---|---|
| 10581 | 2004.03.24 | 1 | 1 | S05W55 | 0100 | HSX |
area was 0060 at midnight |
| 10582 | 2004.03.25 | 7 | 1 | N14W51 | 0140 | CSO |
classification was HSX at midnight, area 0120 |
| 10584 | 2004.03.27 | S13W68 | plage | ||||
| 10585 | 2004.03.27 | S15W40 | plage | ||||
| 10587 | 2004.03.28 | 16 | 20 | S13W03 | 0130 | EAO |
area was 0170 at midnight |
| 10588 | 2004.04.01 | 4 | 1 | S12E51 | 0070 | DSO |
classification was HSX at midnight, area 0060 |
| S380 | emerged on 2004.04.03 |
7 | S16E51 | 0030 | CAO |
split off from region 10588, reversed polarity |
|
| Total spot count: | 28 | 30 | |||||
| SSN: | 68 | 80 | |||||
| Month | Average solar flux at Earth |
International sunspot number | Smoothed sunspot number |
|---|---|---|---|
| 2000.04 | 184.2 | 125.5 | 120.8 cycle 23 sunspot max. |
| 2000.07 | 202.3 | 170.1 | 119.8 |
| 2001.12 | 235.1 | 132.2 | 114.6 (-0.9) |
| 2003.03 | 131.4 | 61.1 | 74.0 (-4.3) |
| 2003.04 | 126.4 | 60.0 | 70.1 (-3.9) |
| 2003.05 | 115.7 | 55.2 | 67.6 (-2.5) |
| 2003.06 | 129.3 | 77.4 | 65.0 (-2.6) |
| 2003.07 | 127.7 | 83.3 | 61.8 (-3.2) |
| 2003.08 | 122.1 | 72.7 | 60.0 (-1.8) |
| 2003.09 | 112.2 | 48.7 | 59.5 (-0.5) |
| 2003.10 | 151.7 | 65.5 | (58.0 predicted, -1.5) |
| 2003.11 | 140.8 | 67.3 | (55.9 predicted, -2.1) |
| 2003.12 | 114.9 | 46.5 | (53.3 predicted, -2.6) |
| 2004.01 | 114.1 | 37.2 | (49.1 predicted, -4.2) |
| 2004.02 | 107.0 | 46.0 | (44.5 predicted, -4.6) |
| 2004.03 | 112.0 | 48.9 | (41.7 predicted, -2.8) |
| 2004.04 | 109.4 (1) | 8.9 (2) | (39.6 predicted, -2.1) |
1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
2) Unofficial, accumulated value based on the Boulder (NOAA/SEC) sunspot number. The official international sunspot number is typically
30-50% less.
This report has been prepared by Jan Alvestad. It is based partly on my own observations and analysis, and partly on data from some of these solar data sources. All time references are to the UTC day. Comments and suggestions are always welcome.
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